Some writers characterize Acnologia as a misunderstood loner. They show that his actions of destruction are a result of his past traumas. Others might make him more of a power - hungry villain who just wants to rule over all. There are also those who give him a sense of humor, which is a very different take from his usual brooding and menacing self in the original series.
The characters in Fairy Tail would have a wide range of reactions. Makarov, as the guild master, would be very cautious. He would need to ensure that Acnologia's presence doesn't put the guild in more danger. Happy would be constantly on guard around Acnologia, ready to fly away at the first sign of trouble. The Thunder Legion would likely be in a state of high alert. However, some of the more adventurous members like Cana might see it as an opportunity for great adventures and powerful new magic. It would be a complex situation with different characters having different stances based on their personalities and past experiences.
Well, it depends on the nature of the fanfiction. Some anime characters might be amused if the fanfiction is light - hearted and full of comical situations. For example, if it's a fanfic about a cooking competition among the characters from a shonen anime, they might react with good - natured laughter and competitiveness. They could also be confused if the fanfiction takes their story in a very strange or unexpected direction, like suddenly making a character from a historical anime end up in a space adventure.
Some members might be initially cautious. Given her past as a powerful and somewhat feared being, they would be worried about her true intentions. For example, Gray might be on guard until he sees her actions are genuine.
There could be characters who are outraged. If the fanfiction distorts their personality or makes them do things completely against their nature, they may be very angry. For example, a noble character made to act like a coward in the fanfiction would likely not take it well.
The guild as a whole would likely mobilize. Erza would start formulating a strategic plan. She'd consider the strengths and weaknesses of Acnologia and figure out the best way to approach the situation. Gray would also be ready to fight, using his ice - make magic to support the rescue mission. They would all be united in their determination to get Lucy back safely.
One element is the lyrics. If the lyrics are about dark topics like death, ghosts, or curses, it can be scary. For example, lyrics that describe a spooky encounter with a supernatural being. Another is the tone of the rap. A slow, deep, and menacing tone can add to the scariness. Also, the setting where the rap takes place. If it's in an abandoned place like an old factory or a haunted house, it gives a creepy vibe.
They could be angry. Consider a character like Ichigo from Bleach. If the fanfiction makes him look weak or changes his character in a way that goes against his core values, he would likely be furious. After all, he has his pride as a Soul Reaper and a protector.
A few might be angry. If the fanfiction shows them in a negative light or changes their backstory in a way they don't like, they could get really mad. For example, if a character with a noble past is made into a villain in the fanfiction, they'd be furious.
Well, here's one. In a small town, there was a rap battle. A young rapper named Jay took part. He rapped some really bold lyrics. But after the battle, he started having nightmares. In his dreams, he was in a dark room and a shadowy figure was rapping at him, criticizing his skills. Every night the dream got worse, and the figure got closer. One day, he decided to stop rapping, and the nightmares finally ceased.